Genetic counseling: Cerebral Palsy
Cerebral palsy Contracting *What is your understanding of why you were referred to genetics? *What questions or concerns would you like us to address today? *Set agenda for the session Etiology *Heterogeneous group of conditions usually leading to ataxia *Sometimes inherited in autosomal dominant, autosomal recessive, or X-linked form in familial cerebellar hypoplasia **Congenital and childhood-onset ataxias tend to be autosomal recessive **Adult-onset conditions tend to be autosomal dominant *May also be due to teratogenic insults **Methymercury **Retinoic acid **Anticonvulsants *Most common cause is hypoxic/ischemic injury in perinatal period or early childhood **Anoxia **Trauma to the brain at birth *Can be caused by cerebral injury later in life Clinical Features *Several classes with different features *Spastic diplegia **Onset several weeks or months after birth ***Delay in normal development, especially motor skills ***Results from prenatal or perinatal insult **Walking attempted much later and results in characteristic stance and gait ***Legs advanced stiffly in short steps like arc of circle ***May have scissors gait with crossing over of legs ***Lower legs splayed out, feet flexed and turned in, heels not touching ground ***Posture alternates between extremes of supination and pronation ***Walking accompanied often by rotary movements of neck and facial grimacing **Legs short and small but muscles not atrophic **Arms may also be mildly affected *Hemiplegia **Difference in function of right and left extremities noticed after birth or 6-12 months **Accounts for about 1/3 of children with cerebral palsy **Affects arms first, noticed in legs when learning to walk **Mental defects depend on whether brain lesion confined to one hemisphere **Convulsions (35-50%) **Seizures may accompany onset if develops during childhood ***Usually limited to hemiplegic side of body ***May persist throughout life *Double hemiplegia **Occurs less frequently than hemiplegia **Bilateral weakness of face, arms, and legs **Begins at any age due to acquired cerebral disease ***May be due to bilateral cerebral lesion or high cervical cord lesion ***May also be produced in infant by fracture-dislocation of cervical spine by breech delivery **Arms severely affected *Congenital choreoathetosis **Recognized after several months or a year **Causes some combination of chorea, athetosis, ballismus, myoclonus, and dystonia **Causes defect in voluntary movement ***May be mild resulting in "fidgets" ***May be severe, intense involuntary movements ***Even with rehabilitation, the most severe rarely achieve enough motor control to live independent life **Intelligence may not be affected *Kernicterus **Was common when postnatal serum bilirubin was kept below 15 mg/dL **Majority of infants die within 1 or 2 years **Survivors usually mentally retarded, deaf, and totally unable to sit, stand, or walk ***Several patients reportedly were not mentally retarded and learned to walk backwards ***Have rigid limbs Management/Treatment Options *Outcome depends on severity of associated intellectual handicaps *Early application of stretching to prevent contractures *Orthopedic appliances and surgical procedures to improve mobility *Special education to help with motor problems and intellectual involvement *Prevention is great challenge **Prevention of kernicterus by phototherapy has helped **Providing low-birth weight infants with extra care may help ***More prone to respiratory distress ***Must provide good surveillance of respiratory function Differential Diagnosis *Leukodystrophy - spinal tap showing elevated spinal fluid indicates leukodystrophy *Hydrocephaly if child has large head *Tumor of cerebral hemishphere - disease is progressive *Spinal cord lesions - weakness limited to lower extremities *Muscular dystrophy - tendon reflexes would be normal *Ataxia telangiectasia Recurrence Risks *Depends if cause of cerebral palsy can be determined *Autosomal recessive **Each pregnancy from heterozygote parents has 25% risk of child being affected **Each pregnancy has 50% risk of being carrier *Autosomal dominant **Each child born to affected parent has 50% chance of being affected **May also occur due to new mutation so low recurrence risk *X-linked **Sons of affected males not affected **Daughters of affected males must be affected **Daughters of carrier females 50% risk of being carriers **Sons of carrier females 50% risk of being affected *Most cases probably caused by hypoxic or ischemic injury to brain so recurrence risk is low Psychosocial Issues *Parental guilt *Burden of disease that requires daily management *Social stigma *Financial pressures, disruption of daily activities for special therapies, orthotics, or other needs *Potential need for lifetime care References *"Abnormalities of Motor Function (Cerebral Palsy)." Principles of Internal Medicine (1994): 2342. *"Cerebellar Hypoplasias." Principles and Practice of Medical Genetics (1997): 2154-2156. *"Cerebral Palsy (Little Disease)." Textbook of Pediatrics (1979): 1759-1761. Notes The information in this outline was last updated in 2002. Material obtained under GFDL Licence from http://en.wikibooks.org/wiki/Handbook_of_Genetic_Counseling